A fan generally has a fan housing with integrated reinforcing ribs, a base (also called a “flange”) with bearings arranged therein, a securing mechanism for the rotor shaft, and a stator with a circuit board mounted on an adjacent flange. DE 200 12 673 U1 (assigned to Papst-Motoren and corresponding to EP 1,076,398) discloses such a fan, comprising essentially a stator, a lamination stack, a winding, a stator tube, a circuit board, and a rotor. The rotor comprises essentially rotor magnets, a rotor bell or cone on which fan blades are arranged, and a rotor hub.
In the case of electric motors which are installed in so-called “clean rooms” or in moist or aggressive environments, it is necessary to provide the sensitive parts of a motor, e.g. the winding and circuit board, with a protective layer or barrier, in order to satisfy high insulation and protection requirements, i.e. such a fan must have a specified kind of protection, depending upon its use.
Thus, it is known, for example from WO 98-19382 and corresponding U.S. Pat. No. 5,973,424, to coat the stator of a electric motor with plastic resin. The object of this disclosure is essentially to provide the connection between stator and circuit board in simpler form. Methods of creating such a protective coating, such as dipping, submerging, vacuum-impregnating, vacuum die-casting, and dripping-in, are known in the prior art.
Nevertheless, it is recognized that these methods not only require mechanical post-processing, but also fail to satisfy the requirements of the higher protection standards.